Carbon bisulfide production method



July 12, 1955 K. w. GUEBERT CARBON BISULFIDE PRODUCTION METHOD Filed May 28, 1951 United States Patent a i 9 Patented Jui' i2 1955 CARBON BISULFDE PRDUCTION METHOD Kenneth W. Guebert, Freeport, Tex., assigner to rhe Dow Chemical Company, Midland, Mich., a corporation of Delaware Appncafion May 2s, issi, serial No. 228,732

4 claims. (ci. zs-zss) This invention relates to a carbon bisultide production method, and, more particularly, to a novel catalytic process of such type using sulfur and a parafdnic hydrocarbon as starting materials.

it was known prior to the present invention that parafnic hydrocarbons and sulfur, in liquid phase or in vapor phase, would react at elevated temperatures to produce carbon bisulfide and hydrogen sulfide. It was also known that this reaction was catalyzed by certain agents, such as Silica gel, fullers earth, bauxite, activated alumina, copper phosphate, zirconium phosphate, and thorium phosphate.

The present invention is based upon the discovery of a novel catalytic agent for the reaction between sulfur and a paratiinc hydrocarbon.

According to the invention carbon bisuliide is produced by contacting a vapor phase mixture of sulfur and a paraftinic hydrocarbon with a magnesium silicate catalyst at a temperature from 500 to 700 C.

The magnesium silicates that are suitable as catalysts are in the amorphous form, and contain Mg() and SiG2 in a mol ratio of from 1:2 to 1:4, preferably in a mol ratio of 1:3. They may also have as much as 20 per cent by weight of adsorbed water. Such an amorphous material is marketed commercially as magnesium silicate by Harshaw Chemical Company.

The process of the invention may be more readily understood by reference to the accompanying drawing, which is a schematic ilow sheet illustrating the production of carbon bisulfide, using a magnesium silicate catalyst.

Liquid sulfur from a supply 11 ows through a line 12 and into a line 13 where it is mixed with natural gas from a supply 14 which hows through a line 15 into the line 13. The natural gas-sulfur mixture passes through the line 13 into a vaporizer 1-5, and from thence through a line 17 to a reactor 10 packed with the magnesium silicate catalyst. Reaction products pass from the reactor through a line 19 to a sulfur condenser 20 where any unreacted sulfur is removed. Products remaining pass from the sulfur condenser through a line 21 to a cooled trap 22 Where carbon bisuliide and some hydrogen sulfide are condensed and collected. The remaining products, mainly H28, then iiow through a line 23 to a scrubber 24 where hydrogen sulde is absorbed by dilute aqueous sodium hydroxide that is p'assed into the scrubber through a line 25. Relatively dilute sodium suliide passes from the bottom of the scrubber through a line 26. A small amount of oy-product leaves the scrubber through a line 27.

The method of the invention is suitable for the production of carbon bisultlde at temperatures ranging from 500 to 700 C. However, it is preferred to carry out the process at temperatures from 560 to 600 C., as reaction proceeds at a practical rate within the above temperature range, and corrosion of metallic reaction apparatus is minimized. The reaction proceeds satisfactorily at atmospheric pressure, although either reduced or elevated pressures can be used if desired.

It is practical to carry out the process of the invention using a space velocity from 200 to 1200. Space velocity is defined as the ratio of total volume of the gases, calculated at 0 C. and 760 mm. Hg total pressure, passed over the catalyst per hour divided by the apparent volume of the catalyst. Within the above range, the selection of a lower space velocity results in a higher yield, but a lower production rate per unit of reactor volume. Accordingly, the space velocity used in a given application is a compromise between these two factors. lt is usually preferred that the space velocity be from 700 to 900.

ln general, any available source of paraiiinic hydrocarbon gases can be used in carrying out the process of the invention. Natural gas provides a convenient supply, preferably a natural gas high in methane. Although it is feasible to carry out the reaction of the invention using a substantial excess either of sulfur or of the parailnic hydrocarbon, it is usually preferred to use from to 110 per cent of the sulfur theoretically required to convert all the carbon in the parainic hydrocarbon to carbon bisulfide, and all the hydrogen therein to hydrogen suliide.

Example Carbon bisulde was produced from a Texas natural gas containing about 90 per cent by volume of methane by passing a vapor mixture of sulfur and the natural gas, in a weight ratio of about l5 parts of natural gas per parts of sulfur, over an amorphous magnesium silicate containing magnesium oxide and Silicon dioxide in a mol ratio of 1:3 in the form of particles of from 8 to 14 mesh U. S. Sieve Series, at a space velocity of 890. The per cent conversion of natural gas charged to carbon bisuliide was found to be a function of temperature, ranging from 44 per cent conversion at a reaction temperature of 544 C., to a 50 per cent conversion at a reaction temperature of 550 C., to 62 per cent conversion at a reaction temperature of 580 C., and 80 p'er cent conversion at a reaction temperature of 611 C.

i claim:

l. A method of producing carbon bisulde that comprises contacting a vapor phase mixture of sulfur and a parathnc hydrocarbon with a catalyst consisting of amorphous magnesium silicate consisting essentially of magnesium oxide and silicon dioxide combined in a mol ratio of from 1:2 to 1:4 and containing up to 20 per cent by weight of adsorbed water at a temperature from 500 to 700 C.

2. A method as claimed in claim 1 in which the temperature is from 560 to 600 C.

3. A method of producing carbon bisulfide that comprises contacting a vapor phase mixture of sulfur and methane with a catalyst consisting of amorphous magnesium silicate consisting essentially of magnesium oxide and silicon dioxide combined in a mol ratio of 1:3 and containing up to 20 per cent by weight of adsorbed Water at a temperature from 560 to 600 C.

4. A method as claimed in claim 3 in which the space velocity is from 200 to 1200.

References Cited in the le of this patent UNlTl-ED STATES PATENTS 2,079,543 Bley May 4, 1937 2,173,085 Cummins Sept. 19, 1939 2,187,393 de Simo Jan. 16, 1940 2,330,934 Thacker Oct. 5, 1943 2,369,377 Thacker Feb. 13, 1945 2,428,727 Thacker Oct. 7, 1947 2,565,215 Poll/ ins et al Aug. 21, 1951 2,616,793 Folkins et al Nov. 4, 1952 OTHER REFERENCES Kalichevsky et al., Chemical Refining of Petroleum, 1933, pages 173-177. 

1. A METHOD OF PRODUCING CARBON BISULFIDE THAT COMPRISES CONTACTING A VAPOR PHASE MIXTURE OF SULFUR AND A PARAFFINIC HYDROCARBON WITH A CATALYST CONSISTING OF AMORPHOUS MAGNESIUM SILICATE CONSISTING ESSENTIALLY OF MAGNESIUM OXIDE AND SILICON DIOXIDE COMBINED IN A MOL RATIO OF FROM 1:2 TO 1:4 AND CONTAINING UP TO 20 PERCENT BY WEIGHT OF ADSORBED WATER AT A TEMPERATURE FROM 500* TO 700* C. 